Radiology of rabbits – Master class (Proceedings)

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Radiology of rabbits – Master class (Proceedings)

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Oct 01, 2008

Normal and abnormal radiographs of a variety of conditions in the pet rabbit will be presented. Medical and surgical treatment of the conditions will be briefly presented as well. This is not intended to be an exhaustive presentation of physiology and treatment of all of these conditions, but rather an introduction to common radiographic findings.

Abdomen

Gastrointestinal tract - normal

It is normal to see some gas present in the gastrointestinal tract (GIT). This is due to the production of gas by bacteria as they process the high fibre foods that rabbits consume. Another normal feature of the GIT is that there is always material present in the stomach. The GIT transit time in rabbits is 3-5 days. The caecum can be small or large depending on the time of day and whether or not the rabbit is in the process of producing hard faeces or caecotropes.

Stomach – abnormalities

If anesthesia is used, a gas shadow is often seen around the ingesta due to aerophagia during induction. This can be indicative of dehydration. True hairballs are rare in rabbits. Hypomotility disorders are relatively common.

A common abnormality of the stomach that is diagnosed by physical exam and radiographs is bloat. The exact aetiology of this condition is unknown. Factors that contribute to this condition are the tight esophageal sphincter and the acutely curved pyloric outflow tract. It is possible to manage this condition medically, but great care needs to be taken to monitor these patients closely. Surgical intervention is often necessary. These patients need to be treated as an emergency. The bloated stomach creates pressure on the diaphragm, which makes it difficult for the rabbit to breath. These patients frequently presently severely compromised and hypothermic. Supplemental heat needs to be supplied and an intravenous catheter should be placed for fluid support immediately. The patient should be anaesthetized and placed in left lateral recumbency. A 12 Fr red rubber catheter with extra fenestrations in it is passed into the stomach. This will help to immediately relieve pressure by the removal of gas and fluid. After as much fluid and gas as possible is removed, 10cc of water with approx ¼ - ½ teaspoon of epsom salts is instilled into the stomach and the rabbit is recovered from general anaesthesia. The rabbit is then given 1-2mg/kg of diazepam to keep it calm and in left lateral recumbency. This helps to keep pressure off of the pyloric outflow tract. The rabbit needs to be supported with supplemental heat during this recovery time. The stomach is gently massaged and monitored every 15-30 minutes. If the stomach stays tight feeling and starts to enlarge again, surgery should not be delayed. It is usually a dried hard piece of ingesta that is obstructing the distal duodenum. In approximately 50% of the cases rabbits can be carefully managed medically to get this material softened and passed.

Intestinal obstruction vs. ileus

Distinguishing obstructions versus ileus in rabbits is not an easy call! Technically, if gas does not extend all the way to the rectum and if the loops of intestine make very tight turns, it is most likely obstruction. This is easier to distinguish if the obstruction is in the upper GIT. However, due to the amount of gas that accumulates in the rabbit intestine, it can be challenging to identify obstruction versus ileus. Obstruction of the GIT needs to be managed surgically. Rabbits, in general, do not tolerate surgery of the intestinal tract as well as other species. Great care should be taken for pain relief and supportive care. Ileus is managed medically with gastrointestinal motility drugs, fluids and syringe feeding.

Abdomen – urinary tract disorders: